Trapping a rainbow in a dielectric waveguide

We numerically demonstrate a “trapped rainbow” on a dielectric waveguide - based device. When excited by a broadband incidence, resonant modes of different frequencies are excited with the electromagnetic field of each frequency component stored at its respective location. We report a complete design of the device that does not depend on artificial media (such as metamaterials) whose realization is a problem itself. Different to the previous approaches with plasmonic materials, our device is completely made of dielectrics, thus is ideally immune of ohmic loss. The structure is of planar geometry compatible to the conventional microfabrication technology. This makes it easily integrated with solid state circuits on conventional semiconductor foundries.